Flash apparatus

ABSTRACT

Flash apparatus for use with camera equipment and the like, comprising a lamp connected across a power source and a circuit to cause current to flow through the lamp so as to bring the lamp to full brilliance simultaneously with, or immediately prior to, the opening of the camera shutter. The last mentioned circuit may comprise a timing circuit the operation of which is initiated by a trigger switch. The trigger switch may be built into the flash apparatus or it may be of the remote type. A circuit may also be provided whereby the lamp may be operated at less than full brilliance prior to the opening of the camera shutter.

United States Patent 1 Sperti et al.

11 3,745,896 [451 July 17,1973

[ FLASH APPARATUS [75] Inventors: George S. Sperti; Albert E. Gerth,

both of Cincinnati, Ohio Related US. Application Data [63]Continuation-impart of Ser. No. 672,618, Oct. 3,

8/1959 Most 315/241 P X 2,877,385 3/1959 Rock 315/241 P X 1,988,0221/1935 Smith 3,259,797 7/1966 Heine 315/247 X Primary ExaminerSamuel S.Matthews Assistant Examiner-Monroe H. Hayes Attorney-Melville, Strasser,Foster & Hoffman [57] ABSTRACT Flash apparatus for use with cameraequipment and the like, comprising a lamp connected across a powersource and a circuitto cause current to flow through the lamp so as tobring the lamp to full brilliance simultaneously with, or immediatelyprior to, the opening of the camera shutter. The last mentioned circuitmay comprise a timing circuit the operation of which is initiated by atrigger switch. The trigger switch may be built into the flash apparatusor it may be of the remote type. A circuit'may also be provided wherebythe lamp may be operated at less than full brilliance prior to theopening of the camera shutter.

15 Claims, 27 Drawing Figures PAFENEED 1 75m 3. 745.896

sum 2 OF 5 Fi g. 10

I NVENTOR/S GEO/20E S. SPERT/c? ALBERT E. GERTH,

XTTORNEYS PAIEN'IEB JUL 1 7 I975 SHEET 3 BF 5 1 l c A 76 2 79 Fig. 19

INVENTORE'S GEORGE 5. SPERTI ALBERT E. GERTH ATTORNEYS PATENIEBJUL 1H975 3 [45, 896

SHEET N [If 5 lNVENTOR/S GEORGE 5. SPERTI ALBERT E, GERTH BY L%(IJJFI,fllla Wild/1 ATTORNEYS PATENTEUJUI 17mm SHEET 5 OF 5 INVENTOR/S GEORGE sSPERTI ALBERT E GERTH FLASH APPARATUS CROSS REFERENCE TO THE RELATEDAPPLICATION This is a continuation-in-part application of US. Pat.application Ser. No. 672,6l8 filed Oct. 3, 1967, in the name of the sameinventors, George S. Sperti and Albert S. Gerth, and entitled FLASHAPPARATUS.

BACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates to flash apparatus and circuitry therefor, and more particularlyto flash apparatus for use with camera equipment and the like.

2. Description of the Prior Art Heretofore illumination of the subjectmatter in photographic procedures has been accomplished in a number ofways. For example, flash bulbs of numerous well known types have beenemployed. Such bulbs are capable of a single use only, and are intendedto be disposable.

Flash means have also been provided which are capable of a plurality ofuses. Such flash means are generally provided with a storage means forelectrical energy and are rechargeable with a given number of flashesobtainable per charge.

An additional well known source of subject matter illumination is thephotoflood lamp. One or-more of 7 these lamps may be used to light thesubject matter, but they operate at maximum brilliance at all times, areunpleasant to the eyes and are characterized by a relatively short life.

In certain embodiments of the present invention the photoflasharrangement utilizes one or more incandescent lamps connected to a powersource. Means may be provided for operating the incandescent lamp orlamps at an initial low-voltage, low-filament temperature level.Additional means are provided for operating the lamp or lamps at a highvoltage, operating filament temperature level at the time the camerashutter is opened.

Operating the lamp or lamps at the initial level accomplishes severalpurposes. The lamps will be at partial brilliance, which is not onlycomfortable to the eye, but which will provide pre-photographillumination of the subject so that the proper arrangement of lights,shadows and the like may be achieved. In addition, the operation of thelamp or lamps at the initial low level will cause them to warm up sothat full brilliance may be reached immediately. If, for example, thelamps were started from a cold condition at the time the camera shutterwas opened, too great a length of time would be required to bring themto full brilliance. Operating the lamps at an initial low-voltage level,and preheating them thereby, prevents mechanical shock to the filamentswhen full voltage is applied. In this'way, lamp life may be increased orlamps characterized by even shorter life but greater brilliance may beused. In accordance with the present invention an incandescent lamp orlamps may be flashed at an extremely high brilliance over and overagain.

In another embodiment a xenon or other gaseous arc lamp is used. A firstlow voltage is applied to the lamp to cause it to illuminate when asecond high voltage, serving as an ignition voltage, is applied to thelamp substantially simultaneously with the opening of the camerashutter.

A timing circuit may be provided in either the incandescent or are lampembodiments so that the lamp is operated at full brilliance for a propertime duration independent of the time for which the trigger switch isheld closed. As will be shown hereafter, the timing circuit provides anumber of advantages including the prolonging of lamp life.

The present invention provides means whereby an incandescent or are lampmay be used in a flash apparatus over and over again. The lamp isconnected directly across the power source (such as a household outletor the like) and the need for a storage means for electrical energy andthe usual time-consuming recharging step has been obviated.

SUMMARY OF THE INVENTION The embodiments of the flash apparatus of thepresent invention comprise at least one arc or incandescent lamp andmeans to operate the lamp at full brilliance substantiallysimultaneously with the opening of the camera shutter. By substantiallysimultaneously, as used here and in the claims, is meant that the lampis brought to full brilliance simultaneously with or immediately priorto the opening of the shutter.

The flash apparatus of the present invention may also be provided with atiming circuit to remove power from the lamp or lamps as quickly aspossible. The invention also relates to means whereby the triggeringswitch may be actuated directly, or indirectly, by electrical, hydraulicor pneumatic means.

It will be understood by one skilled in the art that the flash apparatusof the present invention may be fabricated in any suitable form. Forexample, the flash apparatus may comprise a unit which is an integral ordetachable part of the camera itself, or the unit may comprise acompletely self-contained, wholly separate apparatus. In addition, theflash apparatus of the present BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1is a circuit diagram of the flash apparatus of the present inventionillustrating a resistor in series with the lamp, and a triggering switchby which the resistance may be by-passed.

FIG. 2 is-a circuit diagram similar to FIG. 1 illustrating the use of arectifier means.

FIG. 3 is a circuit diagram similar to FIG. 2 showing a resistor inseries with the rectifier means.

FIG. 4 is a circuit diagram similar to FIG. 2 illustrating the use of asilicon controlled rectifier and an exemplary form of triggeringcircuit.

FIG. 4a is a circuit diagram similar to FIG. 4 but illus trating anotherform of triggering circuit.

FIG. 5 is a circuit diagram similar to FIG. 3 illustrating the use of asilicon controlled rectifier as a part of the triggering mechanism.

FIG. 6 is a circuit diagram of the flash apparatus of the presentinvention wherein two lamps are connected in series until triggering, atwhich time the lamps are switched to a parallel connection.

FIG. 7 is simialr to FIG. 6 and shows the use of a resistorin serieswith the lamps.

FIG. 8 is a circuit diagram showing a silicon controlled rectifier asthe sole series element with the lamp.

FIG. 8a is a circuit diagram similar to FIG. 8 but illustrating the useof a silicon controlled switch.

FIG. 9 is a circuit diagram wherein four rectifier elements comprise abridge circuit in series with the lamp. A silicon controlled rectifieris included, whereby the rectifier bridge may be short circuited overthe conduction phase angle.

FIG. 10 is an electrical diagram of the flash apparatus of the presentinvention illustrating the use of a timing circuit.

FIGS. 11 and 12 are respectively perspective and cross sectional viewsof the hand actuated portion of an hydraulic or pneumatic means forremotely actuating a trigger switch.

FIGS. 13 and 14 illustrate respectively two exemplary forms of atriggering switch with pneumatic or hydraulic means for actuating them.

FIG. I is an exploded view of a portion of a finger actuated triggeringswitch.

FIG. 16 is a cross sectional view of the finger actuated triggeringswitch showing the elements of FIG. 15 in final assembly.

FIG. 17 is an electrical diagram similar to that of FIG. but without thepre-flash illumination means.

FIGS. I8 and 19 are similar to FIG. 10 but illustrate alternateembodiments of the timing circuit.

FIG. 20 is an electrical diagram somewhat similar to the circuit of FIG.10 and illustrating the use of a gaseous arc lamp and a timing circuit.

FIGS. 21 and 22 are similar to FIG. 20 but illustrate alternateembodiments of the timing circuit.

FIG. 23 is an electrical diagram illustrating another embodiment of thepresent invention utilizing an arc lamp and a timing circuit.

FIGS. 24 and 25 are electrical diagrams similar to that of FIG. 23 butillustrating alternate forms of timing circuits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the flashapparatus of the present invention in one of its simplest forms. A lamp1 is connected by leads 2 and 3 to a source of current as at 4. Thesource of current may be, for example, ordinary house current. In suchan instance, the leads 2 and 3 may terminate in a conventionaltwo-pronged plug adapted to be received in a conventional wall socket.

The lamp 1 is connected in series with a resistor 5. The resistor 5 maybe so chosen as to limit the voltage at the lamp terminals to slightlyless than half voltage. Thus, when the lamp I is simply connected to asource of house current or the like, it will glow with a brilliancewhich is comfortable to the eyes, but which is sufficient for thephotographer to determine the position of lights, shadows and the like.A triggering switch 6 is connected in parallel with the resistor 5. Thetriggering switch is adapted to be closed at the time the camera shutteris opened, so that during the interval in which the photograph is beingtaken, the resistor 5 is shorted or by-passed and full line voltageappears across the lamp terminals. When the device is connected toordinary house current, which varies from 105 to 130 volts, the lamp maybe designed to reach full brilliance at about 1 17 volts.

FIG. 2 is similar to FIG. I, and like parts have been given like indexnumerals. The circuitry of FIG. 2 differs from that of FIG. I in that arectifier 7 is substituted for the resistor 5. The rectifier may be ofany suitable type as, for example, a silicon diode rectifier. When thelamp is connected at 4 to a source of AC house current, the rectifierreduces lamp voltage by conduction of only one half cycle. Thus, thevoltage at the lamp terminals will be slightly less than one half thefull AC line voltage, or approximately 45 percent of the line voltage.During the interval when the photograph is being taken, the triggeringswitch 6 will be closed, shorting or by-passing the rectifier 7.

FIG. 3 is similar to FIG. 2, and again like parts have been given likeindex numerals. The circuit illustrated in FIG. 3 differs in that aresistor 8 is placed in series with the rectifier 7. In this way, thelamp voltage may be further reduced during the standby period. As anexample, the resistor 8 may be chosen so as to reduce the lamp voltageby an additional twelve to fifteen volts.

FIG. 4 is substantially the same as FIG. 2 and like parts have beengiven like index numeral s. The circuitry of FIG. 4 differs from that ofFIG. 2 in that the circuit includes a silicon or other controlledrectifier 9 connected in parallel with the rectifier 7. The siliconcontrolled rectifier 9 is adapted to allow current to flow in adirection opposite to the current flow through the rectifier 7 when agate current is applied to the rectifier 9. The silicon controlledrectifier 9 may be connected to any suitable trigger circuitry andswitch. An exemplary form of trigger circuitry may include a battery 10of sufficient voltage to provide satisfactory gate potential, a switch11 and a resistor Ila. When the switch 11 is closed, current limited tothe noted value of the rectifier 9 by the resistor 11a will be suppliedto the gate. Thus the switch 11 should be closed during the intervalwhen a photograph is being taken, at which interval the lamp 1 willreceive full line voltage minus the voltage drop over the rectifyingelement. The lamp 1 should be designed to reach full brilliance at suchvoltage.

FIG. 4a, wherein like parts have been given like index numerals,illustrates another exemplary form of trigger circuitry. In thisinstance the gate of the rectifier 9 is connected through switch II andresistor 11a to lead 3.

The circuit of FIG. 5 is substantially the same as that of FIG. 4 andlike parts have been given like index numerals. As is generallyindicated at 12, the silicon controlled rectifier 9 will be connected toany suitable form of trigger circuitry and switch. The trigger circuitryand switch can, for example, be the same as that illustrated in FIGS. 4or 42. The primary difference be tween the circuitry of FIGS. 4 and 5lies in the provision of the resistor 13, connected in series with therectifier 7. The resistor 13 serves substantially the same purpose asthe resistor 8 in FIG. 3. The resistor I3 is added to further reduce thevoltage across the terminals of the lamp I during the standby period,thus further reducing the illumination during the standby period. Inthis arrangement the lamp 1, on triggering, will receive a lower averagevoltage than in the circuitry of FIG. 4 due to the asymmetrical waveform introduced by the resistor 13. For this reason, the lamp I of FIG.5 should be designed to reach full brilliance at a somewhat lowervoltage than would be the case of the lamp 1 in FIG. 4.

FIG. 6 is a circuit diagram for an embodiment of the present inventionutilizing two lamps. It will be understood by one skilled in the artthat the number of lamps used does not constitute a limitation on thepresent invention.

As shown in the figure, two lamps l4 and are connected respectively byleads 16 and 17 to a suitable source of current (generally indicated at18) such as house current. The lamp 14 is connected by lead 19 to switch20. The lamp 15 is connected by lead 21 to switch 22. One contact ofeach of the switches and 22 are interconnected by lead 23. Thus it willbe noted that when switches 20 and 22 are in the position illustrated,the lamps l4 and 15 are connected in series. The other contact of switch20 is connected to lead 17 by lead 24. Similarly, the other contact ofswitch 22 is connected to lead 16 by lead 25. Thus, when switches 20 and22 are in their alternate position, it will be understood that the lamps14 and 15 will be connected in parallel.

The diagram of FIG. 6 also shows a relay 26 actuable by a trigger switch27. The broken line 28 is used to diagrammatically indicate thatswitches 20 and 22 constitute a part of the relay 26. Thus, when theapparatus of FIG. 6 is connected to a source of electricity, as at 18,lamps 14 and 15 will be in series during the standby pe riod. Also, thelamps 14 and 15 during the standby period will glow with a brilliancewhich will not be discomforting to the eyes. At the time the camerashutter is opened and the photograph is taken, the relay 26, includingswitches 20 and 22, will be actuated by the triggering switch 27.Actuation of the triggering switch 27, and hence switches 20 and 22,will cause the lamps to be connected in parallel, thus allowing fullline voltage to appear across the terminals of each lamp.

FIG. 7 is similar to FIG. 6 and like parts have been given like indexnumerals. The circuit of FIG. 7 differs from that of FIG. 6 in that aresistor 29 is located in the lead 23 between switches 20 and 22. Theresistor 29 is connected in series with the lamps l4 and 15 during thestandby period. In this way, the illumination of lamps 14 and 15 duringthe standby period is further reduced. Actuation of switch 27, and henceswitches 20 and 22, causes the lamps l4 and 15 to be connected inparallel, effectively removing the resistor 29 from the circuit andcausing full line voltage to appear across the terminals of both lamps.

FIG. 8 illustrates another embodiment of the present invention. A lamp30 is connected by leads 31 and 32 to a source of electricity such asordinary house current (generally indicated at 33). A silicon controlledrectifier 34 is located in lead 32 and may constitute the sole elementconnected in series with the lamp 30. A lead 35 is connected acrossleads 31 and 32 and contains a resistor 36, a resistor 37 and acapacitor 38 connected in series. Gate current is supplied to thesilicon controlled rectifier 34 via lead 39 which, in turn, is comnected to lead 35. During the standby or pre-flash period, illuminationof the lamp 30 is achieved by gate current reaching the siliconcontrolled rectifier 34. This gate current is governed by resistors 36and 37, capacitor 33, and a neon lamp 40 having a fixed firing voltageand located in lead 39. It will be understood by one skilled in the artthat the neon lamp may be replaced by any of the solid state devicesdesigned for this purpose, such as a break-over diode or the like. Itwill further be understood that during the standby or preflash period,the silicon controlled rectifier 34 will be triggered at a phase angleof conduction of less than A triggering switch 41 is provided, whichwhen closed connects lead 39 to lead 35 in such a way as to by-passresistor 37. Upon the closing of triggering switch 41, the lamp 30receives rectified half-wave current (by virtue of the siliconcontrolled rectifier 34) and the lamp 30 is accordingly designed toreach full brilliance at this lower average voltage. During flashing,the phase angle of conduction is approximately 180.

It will be understood that, in the circuit diagram of FIG. 8, theresistor 36 will control the current reaching the gate of the siliconcontrolled rectifier during flashing. An adjustment of the gate currentto the proper pre-flash level is accomplished by resistor 37. Thecircuit may also be provided with a diode rectifier 42, constituting aprotective diode to insure that the back gate voltage will not exceedthe limit of the silicon controlled rectifier 34.

FIG. 8a is similar to FIG. 8 and like parts have been given like indexnumerals. The circuitry of FIG. 8a difi'ers from that of FIG. 8 in thatthe silicon controlled rectifier 34 has been replaced by a siliconcontrolled switch 34a. The silicon controlled switch 340 will, whenrendered conductive, permit the passage of alternating current, and maybe the type sold by the General Electric Corporation under the trademarkTRiAC. In this embodiment, the lamp 30 will receive full line voltage(minus the voltage drop over the silicon controlled switch) upon theclosing of switch 41. Further, there is no need for a protective diodesuch as is shown at 42 in FIG. 8. The voltage drop over the siliconcontrolled switch is generally sufficiently small that a lamp designedto reach peak brilliance at full line voltage may be used with goodresults.

FIG. 9 shows an embodiment somewhat simlar to that of FIG. 8, but havingthe advantage that a lamp of normal design for full AC power may beused. In this instance, a lamp 43 is connected by leads 44 and 45 to asource of current (which may be ordinary house current) generallyindicated at 46. The lead 45 contains a bridge circuit (generallyindicated at 47) in series connected with the lamp 43.

The bridge 47 comprises two leads 48 and 49. Lead 48 contains rectifierelements 50 and 51. Rectifier elements 50 and 51 are so oriented in lead48 as to render lead 48 the positive side of the bridge. Lead 49contains rectifier elements 52 and 53. Rectifier elements 52 and 53 areso oriented in lead 49 as to render the lead 49 the negative side of thebridge. The rectifier elements 50-53 may be diode rectifiers.

A lead 54 containing a silicon controlled rectifier 55 is connectedacross leads 48 and 49. A second lead 56, containing a first resistor57, a second resistor 58 and a capacitor 59 is also connected acrossleads 48 and 49. Gate current is supplied to the silicon controlledrectifier 55 by means of a lead 60 connected to the lead 56. The lead 60contains a neon lamp 61 of fixed firing voltage. A triggering switch 62is also provided whereby the lead 60 may be connected to the lead 56 insuch a way as to by-pass resistor 58.

It will be understood by one skilled in the art that in the absence ofcurrent passing through the silicon controlled rectifier 55, the bridgecircuit containing rectifier elements 50-53 will block current to thelamp 43.

In the circuit of FIG. 9, the resistors 57 and 58, the capacitor 59, andthe neon lamp 61 serve the same function as the resistors 36 and 37, thecapacitor 38 and the neon lamp 40 in FIG. 8. When connection is madewith a source of electricity at 46, the lamp will glow with a pre-flashbrilliance governed by the resistor 58 because the silicon controlledrectifier 55 will be triggered in the same way as is the siliconcontrolled rectifier 34 of FIG. 8 during the pre-flash period. A closingof the triggering switch 62 in FIG. 9 will cause a gate current governedby the resistor 57 to reach the silicon controlled rectifer 55. Once thesilicon controlled rectifier 55 is rendered conductive under thesecircumstances, the lamp 43 will have the full line voltage (minus thevoltage drop over the rectifier 55) across its terminals.

FIG. illustrates an exemplary circuit diagram for the flash apparatus ofthe present invention, wherein a timing circuit is used to remove powerfrom the lamp as quickly as possible.

In this embodiment a lamp 63 is connected by means of leads 64 and 65 toa source of current (generally indicated at 66) which, again, may beordinary house current. The lead 64 contains a normally open switch 67.When the lamp 63 is connected to a source of power, as at 66, currentwill by-pass the normally open switch 67 by means of lead 68 containinga rectifier 69. The lead 68 may also contain a resistor 70 in serieswith the rectifier 69 to provide a further reduction of lamp voltageduring the standby or pre-flash period. The circuit thus far describedis similar to that described in connection with either FIGS. 2 or 3(depending upon the presence of a resistor in series with therectifier). The normally open switch 67 comprises one of two switchesforming a part of a relay 71. The relay 71 is connected through normallyopen triggering switch 72 to a capacitor 73. The capacitor 73, in turn,is charged through resistors 74 and 75. Resistors "m and 75 serve toisolate the operator from the power line circuitry and should have asufficiently high voltage rating to prevent arc-through. The capacitor73 is capable of furnishing a measured power pulse sufficient to closethe relay 7t (thus closing switch 67) and sustain the relay in closedposition for a period of time of sufficient duration to cause the lamp63 to flash at full brilliance while the camera shutter is open and thefilm is exposed. The relay 71 then immediately reopens and cannot beclosed again until the capacitor 73 is recharged.

The resistor 74 is connected to a lead 76 which, in turn, is connectedacross the leads 64 and 65. The lead 76 contains a rectifier 77 and acapacitor 78. This rectifier-capacitor combination yields a directcurrent potential equal to the peak of the AC line voltage. The solefunction of this circuit is to provide a direct current source fromwhich the capacitor 73 is charged. When the capacitor 73 is in chargedcondition, a closing of the trigger switch 72 will enable the measuredpower pulse from the capacitor to actuate relay 71 and thus switch 67causing the lamp 63 to receive full line voltage. If, however, duringthe operation of this embodiment the switch 72 were closed for only anextremely short period of time so that the relay was furnished withpower for only such short period of time, the timing function of thisembodiment would be lost. This, however, is prevented by the provisionof the circuit containing switch 79. Switch 79 comprises a part of relay7H and has its contacts so spaced that the slightest motion of the relayarmature will cause normally open switch 79 to close. Switch 79 willremain closed until such time as capacitor 73 is discharged. Thus, thetiming circuit of the embodiment of FIG. 10 is substantially independentof the duration of time for which switch 72 is depressed.

The embodiment of FIG. 10 is particularly suited to be located in aphotoflash housing comprising an integral or separable part of a camera.The lead 64 may contain a switch 80. The switch 80 may be of anysuitable type, such as a push button switch or the like. The switch 80may be included so that lamp power may be applied just prior to theoperation of the camera. Thus, the unit may be connected to a source ofelectricity, as at 66, but will not function until the switch 80 isclosed.

As illustrated, the lead 64 may also include a thermostatic switch 81.The thermostatic switch 81 may be provided so that internal temperaturesof the flash unit may be prevented from rising beyond a safe limit forthe type of material from which the photoflash housing is manufactured.In this way, damage to the photoflash unit or the camera from anoverheating of the flash unit may be prevented.

In all of the embodiments of FIGS. 1-10, circuit protection may befurnished by fuse means or circuit breaker means, as is usual withdevices of this power demand.

In the use of incandescent bulbs of the type described, it is necessarythat they be turned off after a definite short period of time since, atmaximum full brilliancy, the filaments are near failure and areincapable of maintaining full brilliancy for a sustained period of time.One method of preventing filament failure is to provide a timing circuitas illustrated in FIG. 10. Other suitable means may be applied to theembodiments shown in FIGS. 1-9. For example, these embodiments may beprovided with circuit breaker means of well known types, having contactssuited to such use, and provided with actuating means which causes thelamp circuit to be interrupted after a short period of time. Such 'ashort period of time may typically range from one to four seconds,depending upon the nature of the incandescent lamp or lamps being used.In this way, the lamps will be shut off after an appropriate period oftime, irrespective of the length of time for which the triggering switchis held in closed position. Should the circuit breaker open, it must bereset before the flash apparatus may be used again, as is common withapproved devices of this sort. For purposes of an exemplary showingcircuit breakers of the type described are shown at 81a in FIGS. 6-9.

It is within the scope of the present invention to have the flashapparatus thereof built into or constitute an integral part of a cameraitself. In such an instance, the triggering switch of the flashapparatus should be actuated simultaneously with the camera shutterlever, bar or push button. This may be accomplished by any well knownelectrical or mechanical means.

In many instances it is desirable to have the triggering switch actuatedremotely by means controlled by the operator. For example, this isparticularly true in-instances where the trigger switch carries all ofthe current, as in the embodiments of FIGS. 1-3. Such trigger switchactuating means may be controlled, for example, by the hand or foot ofthe operator.

FIGS. 11-16 illustrate an exemplary means whereby the triggering switchmay be remotely actuated. These means comprise hydraulic, pneumatic orelectrical actuators which are located on that finger of the operatorwhich is used to depress the camera shutter lever, bar or push button.An additional advantage of these devices lies in the fact that the flashapparatus of the present invention may be used with any camera withoutrequiring special adaptation of the camera to its use.

One form of remote trigger switch actuator is illustrated in FIGS. 11and 12. The trigger switch actuator is generally indicated at 82 andcomprises a hollow,

bulb 83 and a ring-like member 84. The actuator 82 may be an integralmolded member of any suitable flexible material such as vinyl, rubber,vinyl rubber, neoprene or silicone compounds.

The bulb portion 83 has an integrally molded neck 85 adapted to receivethe end of an elongated, flexible, hollow tubular member 86. The tubularmember 86 may be of any suitable and convenient length, and terminatesin a second bulb (as will be described hereinafter). The juncture of thetubular member 86 and the bulb neck 85 should be both airtight andwatertight. This may be accomplished either frictionally, or by anyother suitable means such as heat sealing, bluing and the like.

FIG. 13 illustrates an exemplary form of triggering switch. In thisembodiment, the switch comprises two strap-like metallic elements ofU-shaped configuration. The downwardly depending end portions 870 and88a of the switch elements 87 and 88 terminate respectively in outwardlyextending flanges 87b and 88b. These flanges may be affixed by anysuitable means (such as rivets, glue or the like) to an insulative basegenerally indicated at 89. It will be understood that the insulativebase and the switch elements may be located within a photoflash housing,a camera case or the like. Wires 90 and 91, connecting the switch withthe rest of the photoflash circuitry may be affixed to the switchelements (as shown) by any suitable means such as soldering or the like.

The contacting portions 870 and 880 of the switch elements 87 and 88 arearranged at right angles to each other with portion 870 overlying andout of contact with portion 880. The portion 87c may be provided with adownwardly extending dimple 92.

As indicated above, the elongated tubular member 86 is provided at itsother end with a second bulb. This second bulb is shown at 93 in FIG.13. The bulb 93 may be made of the same material as the actuator 82 andhas a neck portion 94 adapted to receive the end of the tubular member96 in watertight and airtight fashion. The bulb 93 may be held inposition by any suitable means (not shown). It is within the scope ofthe invention to make the bulb of such size as to fill the area betweenswitch element portions 87a, 87b, 88a and 88b so that the bulb is heldin place by the switch elements themselves.

The system comprising the actuator bulb 83, the bulb 93 and theelongated tubular member 86 may be filled with a fluid medium such asair, liquid or the like.

If the actuator 82 is applied to that finger of the operator which isused to depress the camera shutter lever, bar or push button, thedepression of the camera shutter lever will simultaneously cause thesqueezing or collapsing of the actuator bulb 83. For purposes of anexemplary showing, the bulb 83 in FIG. 12 is shown in position against acamera shutter lever 95. The sqeezing or collapsing of the bulb 83 willcause the liquid or gaseous medium in the line 86 to flow toward thebulb 93. The bulb 93 will tend to expand. Since the bulb 93 is locatedbetween the contact portion 88c of the switch element 88 and the base89, expansion of the bulb 93 will cause the switch portion 880 to moveupwardly into contact with the switch portion 87c thereby closing thetriggering switch. The dimple 92 in the switch portion 87c will insure agood contact between switch portions 870 and 880.

FIG. 14 illustrates another form of triggering switch actuable by thebulb 93. In this instance two L-shaped flexible, metallic contacts 96and 97 are affixed in spaced relationship to an insulative base 98 byany suitable means such as rivets 99 and 100. Wires 101 and 102 areaffixed by soldering or the like to the base portions of the switchelements 96 and 97 and connect these elements with the remainder of theflash apparatus circuitry. A U-shaped switch contact element 103 islocated between the switch elements 96 and 97 and is affixed to theinsulative base by suitable means such as rivet 104. The upstandingportions of the switch element 103 are located near and in spacedrelationship to the upstanding portions of the switch elements 96 and97. The bulb 93 is held (by suitable means not shown) between theupstanding portions of the switch element 103.

Depression of the camera shutter lever, and consequent squeezing of theactuator bulb 83, as described above with respect to FIG. 12, will causeexpansion of the bulb 93. Expansion of the bulb 93 will cause theupstanding portions of switch element 103 to come into contact with theupstanding portions of switch elements 96 and 97, thereby closing thetriggering switch of FIG. 14.

It will be understood by one skilled in the art that as soon as thepressure applied to the actuator bulb 83 is released, the bulb 93 willcontract to its normal shape and the switches of FIGS. 13 and 14 will becaused to open.

FIGS. 15 and 16 illustrate another embodiment of the remote actuator fora triggering switch. In this instance, the actuator comprises anelectrical switch which, when closed, will actuate any suitable form oftriggering switch such as a relay or the like.

It will be noted from FIG. 16 that this embodiment of the remotetriggering switch actuator is similar in appearance to the embodiment ofFIG. 11. The actuator comprises a bulb 105 and a ring-like portion 106.The bulb and ring-like portions may be integral and may be molded of thesame materials outlined with respect to the embodiment of FIG. 11. Inthis instance, however, the bulb portion 105 contains a small pair ofspaced contacts, adapted to come together and complete the circuit whenthe bulb 105 is used to depress the camera shutter lever, bar or pushbutton.

The individual switch elements are most clearly shown in the explodedview of FIG. 15. A piece of insulative material, generally indicated at107, has a peripheral configuration similar to the figure 8 and isfolded in half along the fold line 108 to form two substantiallycircular opposed halves 107a and 10711. The insulative member 107 may bemade of any suitable material such as Mylar or the like. The member 107is provided with a slot 109 located centrally of the fold line 108. a

A pair of contacts are shown at 110 and 111. The contacts 110 and 111may be substantially circular in 2 configuration, each having narrowrearward extensions 110a and 111a respectively. The extensions 110a and111a are adapted to pass through the slot 109 in the member 107. Wiresor leads 112 and 113 are attached (as by soldering, welding or the like)to the extensions 1 a and 1 1 1a respectively, the leads 1 I2 and 113constituting a part of the triggering switch circuitry.

The contact extensions 110a and 1110 may be coated with an insulatingresin, or they may be prevented from short-circuiting by the use of athin T-shaped member of insulative material such as Mylar or the like.The T- shaped member is illustrated at 114. The portion 114a of theT-shaped member is adapted to extend through the slot 109 in the member107 and to lie between the contact extensions 110a and 111a. The portionlI4b of the T-shaped member serves not only to properly locate theT-shaped member but also as a fulcrum for the contacts 110 and 111.

The contacts 110 and 111 may be made of metal or metallized conductingsurfaces on a substrate of insulating material. In assembly (as shown inFIG. 16) the contacts 110 and 111 oppose each other and are affixed tothe portions 107a and 107b respectively of the insulative element 107 byany suitable means such as glue, adhesive or the like.

Depending upon the materials from which it is made, the bulb 105 may bemolded about the various switch elements, or it may be premolded andthen slit as at 105a. The switch elements and leads may be introducedinto and positioned within the bulb via the slit 105a which is thensealed by fusing, cementing or the like. It will be noted from FIG. 16that the contact extensions 110a and 111a, the portion 114a of the T-shaped member and the leads are located in an integral neck portion 115of the bulb 105. To insure that the leads 1 l2 and 113 do notinadvertently become disconnected from the contact extensions, they maybe fused, cemented or otherwise mechanically fastened within the neck115. It will be understood by one skilled in the art that the leads 112and 1113 (as is true of the flexible tubular member 86 in FIG. 11) maybe of any convenient length depending upon the desired placement of theflash apparatus.

The remote trigger switch actuator of FIG. 16 is used in precisely thesame manner as described with respect to the embodiment illustrated inFIG. 12. When the bulb portion 105 is used to depress the camera shutterlever, bar or push button, the contacts 1 10 and 111 will be closedcompleting the triggering circuit. To insure good contact between theelements 110 and 11 1 one of them may be provided with a dimple. Such acontacting dimple is illustrated at 110b in FIGS. 15 and 16.

As indicated above, the various embodiments of the flash apparatus ofthe present invention may be mounted in any suitable type of housing.The housing itself does not constitute a part of this invention. Forexample, the housing may be an integral portion of a camera case, or itmay constitute a completely selfcontained unit adapted to be attached toa camera case or to be hand held. The one or more incandescent lampsconstituting a part of the flash apparatus of the present invention maybe located within the flash apparatus housing, or they may be separatetherefrom and connected thereto by suitably insulated wires. In thelatter instance, for example, the lamps themselves may be suitablymounted in appropriate reflectors and supported in tripods or the like,in the same manner as is typical with ordinary photofloods.

In accordance with the teachings of the present invention, the provisionof means for illuminating an incandescent lamp or lamps to an initialpre-flash level with the subsequent flashing of the lamps to fullbrilliance substantially simultaneously with the opening of the shutter,not only adds to the life of the incandescent lamp, but enables the useof incandescent lamps characterized by a shorter filament life and agreater peak brilliance.

In all of the embodiments described above, for a particular bulb or fora particular set of circumstances, it is well within the skill of oneknowledgeable in the art to determine and utilize circuit elements ofthe proper rating. For example, in the circuit of FIG. 7, when lamps 14and 15 were selected such that they would reach peak brilliance at 120volts, it was found that a resistor rated at 12 or 13 ohms would serveadequately as the resistor 29.

In the embodiment shown in FIG. 10 excellent results were achieved whenthe lamp 63 was chosen such as to reach maximum brilliance at 120 volts.Under such circumstances, a 6 to 12 ohm resistor may be used at 70, anda 220,000 ohm resistor may be used at 74 and 75. A relay of 5,000 ohmsresistance was used successfully together with a six microfaradcapacitor (at 73) capable of withstanding peak line voltage. A 0.02microfarad capacitor capable of withstanding peak line voltage was usedat 78.

FIG. 17 is an electrical diagram substantially identical to that of FIG.10 and like parts have been given like index numerals. FIG. 17illustrates the circuit of FIG. 10 without the pre-flash illuminationfeature. This is accomplished simply by eliminating from the circuit ofFIG. 10 the switch 80, the lead 68 and its elements 69 and 70. In allother respects, the operation of the circuit of FIG. 17 is identical tothat described with respect to FIG. 10.

In the circuit of FIG. 17 the lamp 63 may be an ordinary photoflood.Such a lamp is particularly adapted to withstand the sudden applicationof power. It will be noted that the thermostatic switch 81 of FIG. 10 isnot present in FIG. 17. In general, such a switch is not requiredbecause the circuit of FIG. 17 does not contain the pre-flash resistor70 (of FIG. 10) which would have a tendency to give off heat. Inaddition, the lamp 63 will be illuminated for a very short time. Itwould be within the scope of the invention to include a fuse or curcuitbreaker in the circuit of FIG. 17. However, in general these devices arealso not necessary because, if the relay is properly designed, theordinary house fuse will take care of any overcurrent.

When lamp 63 of FIG. 17 comprises a photoflood, it would be preferableto arrange the trigger switch 72 in such a way as to be closedimmediately prior to actuation of the camera shutter switch. This wouldenable the photoflood to reach full brilliance. As a consequence, theembodiment of FIG. 17 is an ideal situation for the use of the triggerswitch mechanisms of FIGS.

11 through 16.

FIG. 18 is similar to FIG. 17 and like parts have been given like indexnumerals. FIG. 18, however, illustrate a modified form of the timingcircuit.

It will be understood that the like parts of FIGS. 17 and 18 serve thesame functions. In FIG. 18, however, a silicon controlled rectifier 116in series with the relay 71 has been substituted for relay switch 79(FIG. 17). The normally open triggering switch 72 is connected to thegate of the silicon controled rectifier 116. A resistor 177 is in serieswith the triggering switch 72 so as to furnish proper current. Finally,a desensitizing resistor 1 18 may be provided, as is well known in theart.

As in the case of FIGS. and 17, the capacitor 73 is charged throughresistors 74 and 75, which also serve to isolate the operator from thepower line circuitry. The capacitor 73 will be so chosen as to becapable of furnishing a measured power pulse sufficient to close relay71 and sustain the relay in closed position for a period of time ofsufficient duration to cause the lamp 63 to flash at full brilliancewhile the camera shutter is open and the film is exposed. The capacitor73 will actuate the relay 71 in this manner once the triggering switch72 is closed and gate current is applied to the silicon controlledrectifier 116. Thereafter, irrespective of whether or not the triggeringswitch 72 is closed, the silicon controlled rectifier 116 will permitcurrent flow to the relay 71 until such time as the charge in thecapacitor 73 is depleted below the holding current value of the siliconcontrolled rectifier.

FIG. 19 illustrates a circuit diagram similar to FIG. 18 (like partshaving been given like index numerals) with another modification of thetiming circuit. Those elements having been given like index numerals inFIGS. 18 and 19 serve the same purposes.

In this embodiment, the gate of the silicon controlled rectifier 116 isconnected to the lead 65 through a capacitor 119 and a resistor 120. Thenormally opened triggering switch 72 is connected from this lastmentioned lead to that lead containing the capacitor 73, the siliconcontrolled rectifier 116 and the relay 71. Again, the capacitor 73 ischarged through resistors 74 and 75. In this embodiment the operator isisolated from the power line circuitry by resistor 120, as well asresistors 74 and 75. Finally, a lead 121 is provided, having resistors122 and 123 therein. The resistors 122 and 123 are voltage dividerresistors, as is well known in the art, and determine the proportion ofthe available voltage to be allotted capacitor 73 and capacitor 119. Theresistor 120, in addition to its function as one of the means to isolatethe operator from the power line circuitry, also serves to limit thecharging current to the capacitor 1 19 through resistor 118 to a valuesuch that the gate of the silicon controlled rectifier 116 will not beactuated.

The operation of the circuit of FIG. 19 may be described as follows. Thecapacitor 73 is charged through resistors 74 and 75. The capacitor 119is charged through resistor 120. As indicated above, the availablevoltage to be allotted to capacitors 73 and 119 is regulated by thevoltage divider resistors 122 and 123. When the normally open triggeringswitch 72 is closed, capacitor 119 discharges into the gate of siliconcontrolled rectifier 116 causing it to conduct, This in turn, actuatesrelay 71 resulting in the closure of switch 67. Relay 71 will continueto be actuated until the charge on capacitor 73 is depleted below theholding current of silicon controlled rectifier 116. At this time,capacitor 73 is substantially discharged. When the silicon controlledrectifier 116 ceases conduction, capacitors 73 and 1 19 will recharge.Thus, it will be apparent that a timing circuit has been provided, whichcircuit is independent of the duration for which the normally opentriggering switch 72 is closed.

The timing circuit of FIG. 19 has the advantage over that of FIG. 18 inthat one terminal of the normally open triggering switch is common tothe ground return of the silicon controlled rectifier 116. This providesfurther freedom from false operation of the silicon controlled rectifierdue to static impluses or the like.

In an exemplary embodiment of the circuit of FIG. 19, the resistor 122may have a value of 220,000 ohms. The resistor 123 may have a value of110,000 ohms. Capacitor 78 may have a value of 0.1 mfd. Resistor mayhave a value of l megohm. resistor 118 may have a value of 1,000 ohms.The value of capacitor 119 will be determined by the type of siliconcontrolled rectifier 116 used. Generally, this value may range from 0.2to 20 mfd. It will be understood by one skilled in the art that thesevalues are exemplary, and are not intended to be limiting since othervalues may be used.

In the circuits of FIGS. 17 through 19 an ordinary photofiood may beused as the lamp 63. The timing circuits of these Figures will increasethe life of the photoflood lamp. In addition, the subject beingphotographed will be far more comfortable than he would be whenphotofloods are used in a conventional manner.

It will be understood by one skilled in the art that the embodiments ofFIGS. 18 and 19 may be provided with pre-flash illumination means in thesame manner described with respect to FIGS. 10. In such an instance, thelamp 63 should be properly choosen for maximum efficiency, as describedwith respect to FIG. 10.

Although the various embodiments of the present invention have beendescribed with respect to the use of filament type lamps, it is withinthe scope of the invention to utilize gaseous arc lamps. In addition tothe various advantages described above with respect to the filament typelamps, including pre-photograph illumination and the like, the use ofgaseous arc lamps in the embodiments described will make possible agreater illumination efficiency.

In operation, the arc of the lamp may be maintained by known meansincluding ballast means, and full power is applied by the means taughtherein. Modifications of the exemplary circuits for gaseous arc lamp usewill be apparent to those skilled in the art.

FIG. 20 is a diagrammatic illustration of a circuit of the presentinvention utilizing a gaseous arc lamp in combination with a timingcircuit similar to that of FIG. 10. In this instance, a gaseous arc lamp124 is connected by a pair of leads 125 and 126 to a source of current(generally indicated at 127). As in the case of the embodiment of FIG.10, the source of current 127 may be ordinary house current. The lead126 contains a resistor 128 which serves not only to nullify any wiringresistance differences encountered when the circuit is connected todifferent sources of house current, but also serves to preventovercurrent to the lamp 124. The line 126 further may contain aprotective device 129 which may take the form of a fuse, circuit breakeror the like. If, for any reason the timing circuit of FIG. 20 shouldfail, or if for any other reason the gaseous arc lamp 124 should fail toturn off, the device 129 will not only protect the flash unit itself,but also the house fuses, or the like, which protect the current of thesource 127.

Lead 130 is connected across leads 125 and 126 and contains a dioderectifier 131 and capacitor 132, which combination comprises a half-waverectifier yielding a direct current potentially equal to the peak of theAC line voltage. A lead 133 is connected to lead 130 through a resistor134. A lead 135 is connected to lead 125 through a resistor 136.. Lead135 also contains a switch 137 which may be described as the triggerswitch. The switch 137 may be actuated remotely, by any of thepreviously described means, or it may be in association with the camerashutter switch.

Across leads 133 and 135 there extends leads 138 and 139. Lead 138contains a capacitor 140. Lead 139 contains a capacitor 141. Finally,leads 133 and 135 are connected to an interrupter generally indicated at142. The interrupter may be of any suitable type for generating anignition potential between a trigger electrode 143 for the lamp 124 andone of the lamp electrodes, sufficient to ignite the arc of the lamp.

in an exemplary form, the interrupter 142 may be of the vacuum enclosedswitch type. Owing to the very fast breaking characteristics of such aswitch, a very high voltage is produced when the switch is used to makeand break current through an inductive device. An exemplary, thoughnon-limiting, form of inductive device may comprise a drive coil 142a,the inductance of which serves the above purpose.

While not so limited, the interrupter switch may be of single reedconstruction. This reed 14l2b is magnetically biased (as at 1420 and142d) to have good sensitivity to the magnetic field provided by thesurrounding coil 1420.

The interrupting frequency is preferably much higher than the linefrequency, so as to insure operation of the lamp 124 at the earliestpossible moment after triggering switch 137 is closed. While theinterrupting frequency does not constitute a limitation on the presentinvention, a frequency of 300 cycles per second has given excellentresults. The duration of illumination of the lamp 124 may extend overmore than one-half of a power cycle. Reignition of the lamp 124 occursso long as sufficient interrupter output voltage is available.

While an exemplary form of interrupter has been described, as indicatedabove it may take other forms. For example, gas filled enclosed contactsor contacts in open air or oil may be used instead of vacuum switchingcontacts. In addition, a single interrupting reed is not required.Standard reed switches may be used if associated with proper drive meanssuch as magnetic bias and a series connected inductive element. Thelatter may be a drive coil or an indepenent inductive means.

It will further be understood by one skilled in the art that means otherthan an interrupter may be used to produce thee high voltage fortriggering the lamp 124. Such means include spark gap-induction coilmeans or solid state means employing switching transistors and othertypes of solid state components. Another possible source of arc ignitionvoltage might be certain types of piezoelectric devices. Such devicescan be used to initiate the operation of a symmetrically emissive arcflash lamp. Under these circumstances, the lamp would have to be turnedoff by means of a circuit breaker, solid state interrupting means or afuse or fusing material.

The lamp 124 may also take various forms. In an exemplary embodiment,the lamp may comprise two electrodes of different structure located atopposite ends of a transparent enclosure. To assist in turning off thearc in the absence of trigger voltage, the electrodes may be dissimilar.in an exemplary, but non limiting example, one electrode may be of thecold cathode type coated with electron emissive material while the otherelectrode may be of the cold cathode type and made of molybdenum,tantalum, tungsten or other material in uncoated condition. Theun-coated electrode tends to be less electron emissive than the coatedone, when unheated.

Further means may be employed to assure that the arc turns off. Forexample, variations in electrode mass may be used to enhance turn-offcharacteristics. In such an instance, the larger electrode tends (for agiven amount of heat) to reach a lower temperature than the firstelectrode, which may be coated coiled tungsten, or the like. The termcoiled" is used in a non-limiting sense and is intended to encompasscoiled, coiled-coil, or a further coiled configuration.

It is also within the scope of the invention to provide the firstelectrode in a solid, tubular, or other configuration to enhance itscold cathode characteristics, all as is common in the art.

Finally, both electrodes may be coated or un-coated if suitable circuitdesign precautions are observed.

The operation of the circuit of FIG. 20 may be described as follows.When the circuit is connected to the source of current 127 a low voltageline current will be applied to the lamp 124 via leads 125 and 126. Thiscurrent is sufficient to illuminate the lamp if the gas in the lamp isionized. This current is controlled by the resistor 128.

At the same time, capacitor is charged through resistors 134 and 136.The values of the resistors 134 and 136 should be chosen to give adesired charging current for capacitor 140. Resistances 134 and 136 alsoserve to protect the operator against accidental harmful contact withground through the camera. The values of resistances 134 and 136 and thesize and capacity of capacitor 140 will also determine the time requiredto charge capacitor 140.

Upon closure of trigger switch 137, there will be a transfer of chargefrom capacitor 140 to capacitor 141. Again, it will be understood by oneskilled in the art that the choice of size and capacity of capacitors140 and 141 will depend upon the desired final results sought to beachieved. While this choice does not constitute a limitation on theinvention, it is preferable to have capacitor 140 be of low capacity andhigh voltage, while capacitor 141 should be of high capacity and lowervoltage. In this way, the preponderance of charge of capacitor 140 willbe transferred to capacitor 141 substantially simultaneously with theclosing of trigger switch 137. Thus, the function of the circuit willnot be dependent upon hold-down time of trigger switch 137.

Once charged, capacitor 141 will serve as a source of direct currentwhich will be transformed into a pulsating high voltage current byinterrupter 142. This high voltage will be transmitted by lead 144 totrigger electrode 143 of lamp 124. With the trigger electrode 143energized, the gas within the gaseous arc lamp 124 will be ionized andthe line current will cause the lamp 124 to illuminate. Lamp 124 will beilluminated until the charge on capacitor 141 has dissipated below thevalue required to energize the trigger electrode 143. Thereafter, lamp124 will turn off.

It will be understood by one skilled in the art that trigger electrode143 may comprise a wire or may be a painted electrode of known type. Itwill further be understood that in the absence of capacitor 141, theduration of illumination of gaseous arc lamp 124 would depend upon theduration of closure of trigger switch 137. In the circuit of FIG. 20,however, even if trigger switch 137 were held closed, there would beinsufficient current through resistors 134 and 136 to keep capacitor 141charged, so long as resistors 134 and 136 and capacitors 140 and 141were properly chosen with respect to their electrical properties.

A timer circuit of FIG. serves not only to render operation of thecircuit substantially independent of the time for which trigger switch137 is closed, but also to control the total power applied to lamp 124.The trigger circuit ensures that gaseous arc lamp 124 will not glow solong as to be damaged or as to get so hot that it will not turn off.

When desired, the circuit of FIG. 20 may contain a return capacitance,shown in dotted lines and generally indicated by index numeral 145.Under normal circumstances, the normal wiring capacitance will be foundsufficient and return capacitance 145 will not be needed.

FIG. 21 is similar to FIG. 20, and like parts have been given like indexnumerals. FIG. 21 illustrates a circuit wherein the interrupter 142 iscontrolled by a timing circuit of the type described with respect toFIG. 18. Thus, resistor 146 corresponds to resistor 117 of FIG. 18.Similarly, the silicon controlled rectifier 147 and the resistor 148corresponds to elements 116 and 118, respectively, in FIG. 18. Finally,a capacitor 149 is con nected across the silicon controlled rectifier147 to protect it, as is well known in the art.

The operation of the triggering circuit of FIG. 21 is substantiallyidentical to that of FIG. 18. The primary difference lies in the factthat the triggering circuit of FIG. 21 drives the interrupter 142,rather than a relay such as the relay 71 in FIG. 18. Again, thecapacitor 140 is charged through resistors 134 and 136 which also serveto protect the operator. Upon closure of the normally opened triggeringswitch 137, gate current (regulated by resistor 146) is applied to thesilicon controlled rectifier 147 which is rendered conductive. As aconsequence, the interrupter 142 will be operated until the charge onthe capacitor is depleted below the value of the holding currentrequired by the silicon controlled rectifier 147.

FIG. 22 is similar to FIG. 20, and again like parts have been given likeindex numerals. In this instance, the triggering circuit taught withrespect to FIG. 19 has been combined with the circuit of FIG. 20. As aconsequence, voltage divider resistors 150 and 151 are equivalent toresistors 122 and 123 of FIG. 19. Similarly, resistors 152 and 153 areequivalent to resistors 120 and 118, respectively, in FIG. 19. Thecapacitor 154 and the silicon controlled rectifier 155 are thecounterparts of capacitor 119 and silicon controlled rectifier 116 inFIG. 19. Finally, a capacitor 156 is connected across the siliconcontrolled rectifier 155 to protect it, as in the case of capacitor 149in FIG. 21. The operation of lamp 124 by interrupter 142 is identical tothat described with respect to FIG. 20. The operation of the interrupter142 by the timing circuit elements is identical to that described withrespect to the operation of the relay 71 in FIG. 19.

FIG. 23 illustrates yet another embodiment of the flash apparatus of thepresent invention. The embodiment comprises an arc lamp 157 similar tothe arc lamps 124 of FIGS. 20 through 22. The lamp is connected by leads158 and 159 to a source of electrical current 160. The source 160 may,for example, be ordinary house current. In the lead 158 there is aresistor 161 which serves the identical purpose described with respectto the resistor 128 in FIG. 20. The circuit may also be provided with afuse or circuit breaker 162.

Generally a 10 amp fuse will be found satisfactory for this purpose.

The circuit of FIG. 23 incorporates a timing circuit identical to thatdescribed with respect to FIG. 10. Thus, the diode 163 and capacitor 164serve the same function as diode 77 and capacitor 78 of FIG. 10.Resistors 165 and 166 are similar to resistors 174 and 175 of FIG. 10.The capacitor 167, relay 168 and locking switch 169 are substantiallyidentical to the capacitor 73, relay 7] and locking switch 79 of FIG.10. A normally open triggering switch is illustrated at 170.

In this embodiment a lead 171 extends between lead 158 and 159. The lead171 contains a switch 172, a fuse 173 and the primary 174a of atransformer generally indicated at 174. The fuse 173, for purposes of anexemplary showing, may be considered a live amp fuse serving to protectthe primary 174a of transformer 174. The primary can sustain operationsfor only a few seconds without burn out, when actuation of thetriggering switch causes closing of the switch 172 via the relay 168.

When switch 172 is closed, the timed (60 cycle) pulse appears across thetransformer primary 174a. The transformer secondary 174b is soconfigured as to have an output of approximately 2,000 volts. Thisoutput is exemplary, since greater or lesser voltages may be used. Acapacitor 175 is series connected with the primary 176a of a radiofrequency transformer generally indicated at 176. Again, for purposes ofan exemplary showing, the transformer 176 may be of 2.5 mh. secondaryinductance.

It will be evident to one skilled in the art that the combination of thecapacitor 175 and the transformer primary 176a receives current from thetransformer secondary 174b. A spark gap is provided, as at 177. Whenswitch 172 is closed at some point near the maximum voltage oftransformer 174, spark gap 177 breaks down, thereby causing a shortcircuit across transformer 174 and discharging capacitor 175 through theare. This, in turn, causes a large voltage to appear across thesecondary 176b of transformer 176. The secondary 176b is connected bylead 178 to the trigger electrode 179 of the lamp 157. Again it will beunderstood that the trigger electrode 179 of lamp 157 may be the same asthe trigger electrode 143 described with respect to FIG. 20.

Thus, when the normally open triggering switch 170 is closed, the timingcircuit will operate in the manner described with respect to FIG. 10.This, in turn, will cause switch 172 to close and the lamp 157 will beilluminated in the manner just described. Since the transformer 174produces spark gap break down on both halves of the alternating circuitcycle, a pulsating radio frequency trigger voltage is produced at l/l20second intervals. When used with a suitable lamp 157, the operation ofthe timing circuit assures turn off.

The circuit of FIG. 23 is best adapted for use with cameras set forrather long exposure times, as it may be late in flashing by as much asl/ 120 second. Longer exposure time adjustments will produce smallervariations in light exposure. The embodiment of FIG. 23 has a greaterdelay in starting (1 [120 of a second) than do the embodiments of FIGS.through 22, which exhibit a delay of about 1/300 of a second.

FIG. 24 is similar to FIG. 23 and like parts have been given like indexnumerals. The electrical diagram of FIG. 24 differs from that of FIG. 23in that it incorporates a timing circuit of the type taught with respectto FIG. 18. Thus, the locking switch 169 of FIG. 23 has been eliminated.Resistors 180 and 181 and silicon controlled rectifier 182 correspond toresistors 117 and ll 18 and silicon controlled rectifier I 16,respectively, of FIG. 18. The timing circuit of FIG. 24 operates in themanner described with respect to FIG. 18. When the relay 168 closes theswitch 172, the lamp 157 is illuminated in the manner described withrespect to FIG. 23.

FIG. is again similar to FIG. 23 and like parts have been given likeindex numerals. FIG. 25 illustrates the application of a timing circuitof the type taught in FIG. 19 to the circuit of FIG. 23. As aconsequence, voltage divider resistors 183 and 184 correspond to theresistors I22 and 123 of FIG. 19. Similarly, resistors 185 and 186correspond to resistors 120 and 118 respectively, of FIG. 19. Thesilicon controlled rectifier 187 and the capacitor 188 correspond to thelike parts 116 and 1 19 of FIG. 19. The timing circuit of FIG. 25 worksin a manner identical to that described with respect to FIG. 19. Whenthe timing circuit, upon closure of normally open triggering switch 170causes actuation of the relay 168, this will result in a closure ofswitch 172. As a consequence, the lamp 157 will flash in the mannerdescribed with respect to FIG. 23.

Modifications may be made in the invention without departing from thespirit of it.

We claim:

1. Flash apparatus for use with photographic equipment and the like,which comprises a circuit containing a gaseous arc lamp and a protectivecurrent limiting device connected in series across a source ofalternating current, triggering means in said circuit which whenactuated causes the passage of current from said alternating currentsource through said lamp to illuminate said lamp, a timing circuit, saidtiming circuit comprising a primary energy storage capacitor, a sourceof high voltage to actuate said triggering means and a normally opentriggering switch whereby closure of said triggering switch will causeactuation of said source of high voltage by a measured pulse from saidprimary energy storage capacitor resulting in the actuation of saidtriggering means and illumination of said lamp every half cycle of saidalternating current and means for maintaining said source of highvoltage in actuated condition until said primary energy storagecapacitor pulse is substantially discharged.

2. The structure claimed in claim I including at least a pair ofresistors isolating said timing circuit from said alternating currentsource, whereby to protect the operator of said photographic equipmentfrom dangerous shock.

3. The structure claimed in claim 1 including a source of directcurrent, a pair of resistors being connected across said source ofdirect current and comprising a voltage divider system, said primaryenergy storage capacitor being connected to said voltage divider systemvia a pair of isolating resistors and in such a way as to receive thelarger portion of the voltage available from said voltage dividersystem, said means for maintaining said source of high voltage inactuated condition comprising a silicon controlled rectifier in serieswith said source of high voltage and with its cathode connected to thenegative terminal of said primary energy storage capacitor, the gate ofsaid silicon controlled rectifier being connected through a triggeringcapacitor and a resistor in series to the negative terminal of saidvoltage divider system, a resistor shunting the gate to said cathode ofsaid silicon controlled rectifier whereby to stabilize the triggeringcharacteristics of said silicon controlled rectifier and to provide areturn path for the charging current of said triggering capacitor, aprotective capacitor in parallel with said silicon controlled rectifier,said triggering switch being connected between the negative terminal ofsaid triggering capacitor and the cathode of said silicon controlledrectifier whereby said source of high voltage will be actuated untilsaid primary energy storage capacitor is substantially discharged,irrespective of the duration of time for which said triggering switch isclosed.

4. The structure claimed in claim 1 wherein said triggering meanspermitting said passage of current from said source of alternatingcurrent through said gaseous arc lamp to illuminate said lamp at fullbrilliance comprises a first relay contact switch, a high voltagestep-up transformer, a spark gap, an excitation capacitor, a radiofrequency transformer and a triggering electrode for said gaseous arclamp, said first relay contact switch and the primary of said highvoltage transformer being connected in series across said source ofalternating current, the secondary of said high voltage transformerhaving at one end two leads, the first of said leads being connected toa spark gap, the second of said leads containing in series saidexcitation capacitor and the primary of said radio frequencytransformer, the secondary of said radio frequency transformer beingconnected to said trigger electrode, a relay having an armature, saidfirst relay contact switch being normally open and being movable to aclosed position when said relay is actuated, said relay being connectedto said primary energy storage capacitor through said triggering switch.

5. The structure claimed in claim 4 wherein said means for maintainingsaid relay in actuated condition comprises a second relay contact switchforming a part of said relay, said second relay contact switch beingnormally open and being movable to a closed position by the slightestmovement of said armature when said relay is actuated, said relay alsobeing connected to said primary energy storage capacitor through saidsecond relay contact switch whereby said relay will be connected to saidprimary energy storage capacitor and said first and second relay contactswitches will remain closed until said primary energy storage capacitoris substantially discharged, irrespective of the duration of time forwhich said triggering switch is closed.

6. The structure claimed in claim 4 wherein said means for maintainingsaid relay in actuated condition comprises a silicon controlledrectifier in series with said relay, the gate of said silicon controlledrectifier being connected to said primary energy storage capacitorthrough said triggering switch and a resistor in series whereby saidrelay will be actuated and said first relay contact switch will beclosed until said primary energy storage capacitor is substantiallydischarged, irrespective of the duration of time for which saidtriggering switch is closed.

7. The structure claimed in claim 4 including a source of directcurrent, a pair of resistors being connected across said source ofdirect current and comprising a voltage divider system, said primaryenergy storage capacitor being connected to said voltage divider systemvia a pair of isolating resistors and in such a way as to receive thelarger portion of the voltage available from said voltage dividersystem, said means for maintaining said relay in actuated conditioncomprising a silicon controlled rectifier in series with said relay andwith its cathode connected to the negative terminal of said primaryenergy storage capacitor, the gate of said silicon controlled rectifierbeing connected through a triggering capacitor and a resistor in seriesto the negative terminal of said voltage divider system, a resistorshunting the gate to said cathode of said silicon controlled rectifierwhereby to stabilize the triggering characteristics of said siliconcontrolled rectifier and to provide a return path for the chargingcurrent of said triggering capacitor, said triggering switch beingconnected between the negative terminal of said triggering capacitor andthe cathode of said silicon controlled rectifier whereby said relay willbe actuated and said first relay contact switch will be closed untilsaid primary energy storage capacitor is substantially discharged,irrespective of the duration of time for which said triggering switch isclosed.

8. The structure claimed in claim wherein said timing circuit isisolated from said main source of alternating current by a pair ofresistors, and including a lead connected across said source ofalternating current and containing a rectifier and a second capacitor inseries, said rectifier and second capacitor combination being connectedthrough said pair of resistors to said primary energy storage capacitorand constituting said source of direct current from which said firstcapacitor is charged.

9. The structure claimed in claim 6 wherein said timing circuit isisolated from said source of alternating current by a pair of resistors,and including a lead connected across said source of alternating currentand containing a rectifier and a second capacitor in series, saidrectifier and second capacitor combination being connected through saidpair of resistors to said primary energy storage capacitor andconstituting said source of direct current from which said firstcapacitor is charged.

10. The structure claimed in claim 1 wherein said source of high voltagecomprises an interrupter switch and an inductive device, saidinterrupter switch adapted to make and break current through saidinductive device.

11. The structure claimed in claim 10 wherein said interrupter switchcomprises a single reed, vacuum enuum enclosed interrupter switch, saidinterrupter switch being magnetically biased whereby to have goodsensitivity to the magnetic field provided by said surrounding coil.

12. The structure claimed in claim I wherein said means for maintainingsaid source of high voltage energized comprises a second capacitorconnected in parallel with said primary energy storage capacitor andsaid source of high voltage, said triggering switch being connectedbetween said primary energy storage capacitor and said second capacitorwhereby said source of high voltage will be energized and saidtriggering means will be energized until said second capacitor issubstantially discharged irrespective of the duration of time for whichsaid triggering switch is closed.

13. The structure claimed in claim 12 wherein said timing circuit isisolated from said source of alternating current by a pair of resistors,and including a lead connected across said source of alternating currentand containing a rectifier and third capacitor in series, said rectifierand third capacitor combination being connected through one of saidresistors to said primary energy storage capacitor and constituting asource of direct current from which said primary energy storagecapacitor is charged.

14. The structure claimed in claim 1 wherein said means for maintainingsaid source of high voltage in actuated condition comprises a siliconcontrolled rectifier in series with said source of high voltage, aprotective capacitor in parallel with said silicon controlled rectifier,the gate of said silicon controlled rectifier being connected to saidprimary energy storage capacitor through said triggering switch and aresistor in series whereby said source of high voltage will be actuateduntil said primary energy storage capacitor is substantially dischargedirrespective of the duration of time for which said triggering switch isclosed.

15. The structure claimed in claim 14 wherein said timing circuit isisolated from said main source of alternating current by a pair ofresistors, and including a lead connected across said source ofalternating current and containing a rectifier and a second capacitor inseries, said rectifier and second capacitor combination being connectedthrough said pair of resistors to said primary energy storage capacitorand constituting a source of direct current from which said primaryenergy storage capacitor is charged.

1. Flash apparatus for use with photographic equipment and the like,which comprises a circuit containing a gaseous arc lamp and a protectivecurrent limiting device connected in series across a source ofalternating current, triggering means in said circuit which whenactuated causes the passage of current from said alternating currentsource through said lamp to illuminate said lamp, a timing circuit, saidtiming circuit comprising a primary energy storage capacitor, a sourceof high voltage to actuate said triggering means and a normally opentriggering switch whereby closure of said triggering switch will causeactuation of said source of high voltage by a measured pulse from saidprimary energy storage capacitor resulting in the actuation of saidtriggering means and illumination of said lamp every half cycle of saidalternating current and means for maintaining said source of highvoltage in actuated condition until said primary energy storagecapacitor pulse is substantially discharged.
 2. The structure claimed inclaim 1 including at least a pair of resistors isolating said timingcircuit from said alternating current source, whereby to protect theoperator of said photographic equipment from dangerous shock.
 3. Thestructure claimed in claim 1 including a source of direct current, apair of resistors being connected across said source of direct currentand comprising a voltage divider system, said primary energy storagecapacitor being connected to said voltage divider system via a pair ofisolating resistors and in such a way as to receive the larger portionof the voltage available from said voltage divider system, said meansfor maintaining said source of high voltage in actuated conditioncomprising a silicon controlled rectifier in series with said source ofhigh voltage and with its cathode connected to the negative terminal ofsaid primary energy storage capacitor, the gate of said siliconcontrolled rectifier being connected through a triggering capacitor anda resistOr in series to the negative terminal of said voltage dividersystem, a resistor shunting the gate to said cathode of said siliconcontrolled rectifier whereby to stabilize the triggering characteristicsof said silicon controlled rectifier and to provide a return path forthe charging current of said triggering capacitor, a protectivecapacitor in parallel with said silicon controlled rectifier, saidtriggering switch being connected between the negative terminal of saidtriggering capacitor and the cathode of said silicon controlledrectifier whereby said source of high voltage will be actuated untilsaid primary energy storage capacitor is substantially discharged,irrespective of the duration of time for which said triggering switch isclosed.
 4. The structure claimed in claim 1 wherein said triggeringmeans permitting said passage of current from said source of alternatingcurrent through said gaseous arc lamp to illuminate said lamp at fullbrilliance comprises a first relay contact switch, a high voltagestep-up transformer, a spark gap, an excitation capacitor, a radiofrequency transformer and a triggering electrode for said gaseous arclamp, said first relay contact switch and the primary of said highvoltage transformer being connected in series across said source ofalternating current, the secondary of said high voltage transformerhaving at one end two leads, the first of said leads being connected toa spark gap, the second of said leads containing in series saidexcitation capacitor and the primary of said radio frequencytransformer, the secondary of said radio frequency transformer beingconnected to said trigger electrode, a relay having an armature, saidfirst relay contact switch being normally open and being movable to aclosed position when said relay is actuated, said relay being connectedto said primary energy storage capacitor through said triggering switch.5. The structure claimed in claim 4 wherein said means for maintainingsaid relay in actuated condition comprises a second relay contact switchforming a part of said relay, said second relay contact switch beingnormally open and being movable to a closed position by the slightestmovement of said armature when said relay is actuated, said relay alsobeing connected to said primary energy storage capacitor through saidsecond relay contact switch whereby said relay will be connected to saidprimary energy storage capacitor and said first and second relay contactswitches will remain closed until said primary energy storage capacitoris substantially discharged, irrespective of the duration of time forwhich said triggering switch is closed.
 6. The structure claimed inclaim 4 wherein said means for maintaining said relay in actuatedcondition comprises a silicon controlled rectifier in series with saidrelay, the gate of said silicon controlled rectifier being connected tosaid primary energy storage capacitor through said triggering switch anda resistor in series whereby said relay will be actuated and said firstrelay contact switch will be closed until said primary energy storagecapacitor is substantially discharged, irrespective of the duration oftime for which said triggering switch is closed.
 7. The structureclaimed in claim 4 including a source of direct current, a pair ofresistors being connected across said source of direct current andcomprising a voltage divider system, said primary energy storagecapacitor being connected to said voltage divider system via a pair ofisolating resistors and in such a way as to receive the larger portionof the voltage available from said voltage divider system, said meansfor maintaining said relay in actuated condition comprising a siliconcontrolled rectifier in series with said relay and with its cathodeconnected to the negative terminal of said primary energy storagecapacitor, the gate of said silicon controlled rectifier being connectedthrough a triggering capacitor and a resistor in series to the negativeterminal of said vOltage divider system, a resistor shunting the gate tosaid cathode of said silicon controlled rectifier whereby to stabilizethe triggering characteristics of said silicon controlled rectifier andto provide a return path for the charging current of said triggeringcapacitor, said triggering switch being connected between the negativeterminal of said triggering capacitor and the cathode of said siliconcontrolled rectifier whereby said relay will be actuated and said firstrelay contact switch will be closed until said primary energy storagecapacitor is substantially discharged, irrespective of the duration oftime for which said triggering switch is closed.
 8. The structureclaimed in claim 5 wherein said timing circuit is isolated from saidmain source of alternating current by a pair of resistors, and includinga lead connected across said source of alternating current andcontaining a rectifier and a second capacitor in series, said rectifierand second capacitor combination being connected through said pair ofresistors to said primary energy storage capacitor and constituting saidsource of direct current from which said first capacitor is charged. 9.The structure claimed in claim 6 wherein said timing circuit is isolatedfrom said source of alternating current by a pair of resistors, andincluding a lead connected across said source of alternating current andcontaining a rectifier and a second capacitor in series, said rectifierand second capacitor combination being connected through said pair ofresistors to said primary energy storage capacitor and constituting saidsource of direct current from which said first capacitor is charged. 10.The structure claimed in claim 1 wherein said source of high voltagecomprises an interrupter switch and an inductive device, saidinterrupter switch adapted to make and break current through saidinductive device.
 11. The structure claimed in claim 10 wherein saidinterrupter switch comprises a single reed, vacuum enclosed switch, saidinductive device comprising a coil, said vacuum enclosed interrupterswitch being series connected with said coil, said coil surrounding saidvacuum enclosed interrupter switch, said interrupter switch beingmagnetically biased whereby to have good sensitivity to the magneticfield provided by said surrounding coil.
 12. The structure claimed inclaim 1 wherein said means for maintaining said source of high voltageenergized comprises a second capacitor connected in parallel with saidprimary energy storage capacitor and said source of high voltage, saidtriggering switch being connected between said primary energy storagecapacitor and said second capacitor whereby said source of high voltagewill be energized and said triggering means will be energized until saidsecond capacitor is substantially discharged irrespective of theduration of time for which said triggering switch is closed.
 13. Thestructure claimed in claim 12 wherein said timing circuit is isolatedfrom said source of alternating current by a pair of resistors, andincluding a lead connected across said source of alternating current andcontaining a rectifier and third capacitor in series, said rectifier andthird capacitor combination being connected through one of saidresistors to said primary energy storage capacitor and constituting asource of direct current from which said primary energy storagecapacitor is charged.
 14. The structure claimed in claim 1 wherein saidmeans for maintaining said source of high voltage in actuated conditioncomprises a silicon controlled rectifier in series with said source ofhigh voltage, a protective capacitor in parallel with said siliconcontrolled rectifier, the gate of said silicon controlled rectifierbeing connected to said primary energy storage capacitor through saidtriggering switch and a resistor in series whereby said source of highvoltage will be actuated until said primary energy storage capacitor issubstantially discharged irrespective of the duration Of time for whichsaid triggering switch is closed.
 15. The structure claimed in claim 14wherein said timing circuit is isolated from said main source ofalternating current by a pair of resistors, and including a leadconnected across said source of alternating current and containing arectifier and a second capacitor in series, said rectifier and secondcapacitor combination being connected through said pair of resistors tosaid primary energy storage capacitor and constituting a source ofdirect current from which said primary energy storage capacitor ischarged.